Refractory articles made of carbides or comprising carbide components are known to have good properties when used under high temperature conditions. It is therefore desirable to use constructional materials comprising carbide components for heat resistant materials; erosion-resistant materials for electrical technology, which can be used under operating conditions in air; materials for high-temperature heat storage; materials for ablation heat-reflecting systems; and abrasion-resistant and tribotechnical materials. However, it is a problem to produce such articles having a desired shape, especially if the articles shall have a complex form.
U.S. Pat. No. 3,189,472 and U.S. Pat. No. 3,205,043 disclose a method of manufacturing a composite refractory article. This method comprises the steps of mixing of a silicon carbide powder and a carbonaceous material, subsequent forming of an intermediate product by pressing and filling the product containing the silicon carbide and the carbon with silicon. The last step was realized with the use of silicon vapor or molten silicon at a temperature exceeding the melting-point of the silicon.
While penetrating the intermediate product, the silicon is bonded into a secondary silicon carbide using the carbon from the product. By the known method a composite refractory article is obtained. Such an article has a high level of residual stress, moreover it is prone to cracking. U.S. Pat. No. 3,725,015 discloses another method of manufacturing a composite refractory article. The article produced thereby is based on at least one refractory compound. The known method includes the following steps:
mixing of a refractory material powder with a carbonaceous substance; PA1 forming from the mixture obtained an intermediate product of a necessary form and size by pressing; PA1 heating of the obtained intermediate product in order to allocate carbon from the carbonaceous substance; PA1 filling said intermediate product with a molten metal or a mixture of metals, containing 74-99% vol. of at least a metal chosen from the group consisting of: Si, Cr, Fe, Ni, Ti and 1-25% vol. of metal (mixture) chosen from the group, consisting of: Al, Cu, Co, Fe and their mixtures, 0-24% vol. of a metal, which constitutes the metal portion of the refractory material.
This known method does not eliminate residual stress in the product completely, though the level is reduced. Articles having a complicated shape cannot be produced with accuracy by this method due to great shrinkage of the article during the heat treatment. The article produced by this method can have a closed porosity. Such a kind of porosity makes it difficult for a molten metal (mixture) to penetrate into the intermediate product. A complicated equipment for maintaining necessary high temperatures is needed to perform this method.
An article produced by said method represents at least a triple system, consisting of a sintered refractory compound from the group including boron carbide, boron silicide, titanium boride, titanium carbide, zirconium carbide, zirconium boride, silicon nitride, beryllium carbide, boron carbide, their mixtures and an alloy, consisting of at least two metals. A residue volume of space between particles of the article is filled up with said alloy, one of its metal components being the same as the metal forming the refractory material, and another one chosen from the group consisting of: aluminium, copper, cobolt, iron, and their mixtures.
An article produced by said method has a porosity of 10-40% vol.; the space between the article particles which is occupied by the metal carbide is 5-35% vol. The rest 5-35% vol. of said space is occupied by the alloy.